Step 2 included several visits: administration of VOR (visit 3), modified/abbreviated 8 hour PK analysis, leukapheresis procedure and safety follow up (Visit 4). After assessment and ascertainment of safe to proceed clinical status, each participant receive a single dose of VOR 400 mg. Participant remained in the clinic for observation and the collection of samples for the abbreviated PK. Four hours after the dose, the leukapheresis procedure was initiated. It was anticipated that the completion of Step 1 and 2 would occur over a minimum of 8 weeks. All participants must complete Step 2 prior to moving to Step 3. All participants are assessed after the Visit 3 leukapheresis for an in vivo response to the 400 mg of VOR.